From the sounds of it, DON"T run on the sidehill. Just back down to the logs and go straight back up.
If your tractor runs out of power or traction, then you will know to quit that approach.
Better to let the wood rot than risk your hide, especially if you are feeling a need to ask about it.
Explain better how you plan to move the logs? Hooking to the 3 ph ?
Can you comfortably drive your tractor down to these logs, turn around, and drive back up the hill with no wood at all?
If so, that is a start. If not, drop the idea of going down there with your tractor.
Consider a long cable or chains to stay above and drag the logs up the hill. Be very aware that you need to pull straight away, and not at an angle to the pull.
Don't try to get them in the bucket unless you are very confident in what you can and cannot get away with.
Wish you good luck and safe travel.